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Rectangular Patch - RF Cafe Forums
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panagiotis
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Post subject: Rectangular Patch
Posted: Tue May 29, 2007 4:12 pm
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Joined: Thu May 10, 2007
11:14 am Posts: 8 |
hi everybody, I would like to decide about the
length, width, substrate and spacing of the rectangular
patches of a 4-element phased array at ISM. could
u help me with it?
thanks, Panagiotis
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nubbage |
Post subject:
Posted: Wed May 30, 2007 3:55 am
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General |
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Joined: Fri Feb 17, 2006
12:07 pm Posts: 218 Location: London UK
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Hi Panagiotis Which of the ISM bands? 2.4GHz?
I have some design data. Let me know which band,
and I will either send formulas or do the design
4U. BTW: one factoid/rule of thumb I seem to
have gleaned is that the lower the k of the substrate,
the greater the bandwidth for a patch antenna.
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panagiotis |
Post subject:
Posted: Wed May 30, 2007 10:55 am
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Joined: Thu May 10, 2007
11:14 am Posts: 8 |
The array is at 2.4GHz. I design a coupled oscillators
array for my diploma thesis.I have the outputs of
the 4 coupled oscillators and i want to take the
radiation patterns of the phased array. So, I should
know the dimensions of the rectangular pathes,spacing
and etc...
Thank you in advance, Panagiotis
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nubbage |
Post subject:
Posted: Thu May 31, 2007 4:23 am
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General |
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Joined: Fri Feb 17, 2006
12:07 pm Posts: 218 Location: London UK
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Ahh, when I found the design equations they were
for a coaxial feed circular patch at 2.8GHz, with
a complete analysis given for similar frequencies
1 to I guess 8 GHz. (Liang C. Shen Proc IEE Vol
126 No 12) I will continue the search of my design
database for a recatangular patch. Most of what
I have found is about arrays of rectangular patches
with a combining corporate feed network, which is
not exactly what you want. If you are expected
to build one as part of your project, you will need
to have a knowledge of likely substrate permittivity
and thickness. Perhaps while I am searching
the database you could research what substrates
are available for you to use for the antenna model.
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nubbage |
Post subject:
Posted: Thu May 31, 2007 10:00 am
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General |
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Joined: Fri Feb 17, 2006
12:07 pm Posts: 218 Location: London UK
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Hi panagiotis I am now ready to "rock n roll"
with either a rear-fed (from coaxial) or an edge
fed (from microstrip) rectangular patch. We also
have it in round circular patch if you prefer.
All I need now is the material thickness and
epsilon value. For all this, do I get to use
half of your diploma??
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panagiotis |
Post subject:
Posted: Thu May 31, 2007 11:00 am
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Joined: Thu May 10, 2007
11:14 am Posts: 8 |
First of all, thank you nubbage. Second: My work
is to design and materialize the 4 coupled oscillators(4
VCOs coupled by a coupling network) which will give
4 outputs for each element(patch) of the array and
not to materialize the array. So, I do not know
the exact material thickness and epsilon value of
the substrate for the patch. Can u decide about
these values or what should u know from me to decide?
Also, I do not know either a rear-fed (from coaxial)
or an edge fed (from microstrip) rectangular patch
will be appropriate.. It would be very good
for my work to have the design of the patch
Of course u can use half of my diploma
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nubbage |
Post subject:
Posted: Fri Jun 01, 2007 3:42 am
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General |
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Joined: Fri Feb 17, 2006
12:07 pm Posts: 218 Location: London UK
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kali maira Panagiotis Great, thanks for the use
of 50% of your first class diploma.
Your application is now much clearer. But to decide
how the patches are fed with RF we need to determine
if the antenna array is immediately integrated with
the oscillator sources or is placed some distance
away (more than a few cm). If it is integrated,
then a microstrip line and an edge connection through
a quarter wave transformer is called for. If it
is at a distance, then a semi-rigid coaxial line
and a rear feed through the ground-plane is better.
I will assume an integrated structure, and I will
look into what specifications of strip-line board
would be best. The choice is determined mostly by
the band-width you require for the signal. This
will be the fine-tuning range or modulation bandwidth
of the oscillators. Bandwidth and substrate height
from groundplane to trace are directly and almost
linearly proportional in patch antennas. So,
what is the full tuning range of the oscillators?
If fixed in frequency but they will be frequency
modulated, what is the likely frequency deviation
in % of center frequency? Do you need to produce
a predicted radiation pattern for the array for
the thesis report?
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nubbage |
Post subject:
Posted: Thu Jun 07, 2007 4:16 am
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General |
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Joined: Fri Feb 17, 2006
12:07 pm Posts: 218 Location: London UK
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Hi panagiotis The design is ready. Four rectangular
patches on Rogers Duroid 5870 board, each 50 ohm
imedance, centred on 2.45GHz. The bandwidth will
be about 50MHz, so I hope that is enough, as you
did not yet respond to my query about this. Are
you still interested in this antenna? Do you
need a polar radiation pattern computed? It has
been a week since we heard from you.
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panagiotis |
Post subject:
Posted: Thu Jun 07, 2007 6:01 am
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Joined: Thu May 10, 2007
11:14 am Posts: 8 |
Good morning Nubbage, Excuse me for this week,
but i had exams, so, I had to study. Of course
I am still interested in this array. I was ready
to send to you that the desired bandwidth is 50MHz
but you send to me first
.I would be grateful If I had a polar radiation
pattern computed. So, can you send the design to
my e-mail? My mail is
pmourtopallas@gmail.com.
Thank you very much Nubbage for all your interesting.
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panagiotis |
Post subject:
Posted: Thu Jun 07, 2007 6:14 am
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Joined: Thu May 10, 2007
11:14 am Posts: 8 |
and something else, the purpose of my application
is to have a beam scanning of some degrees. By detuning
the end elements (end VCOs) the 4 VCOs are locked
to a new frequency and they create a new phase difference
between elements. With this technique you can succeed
a beam scanning of some degrees.
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nubbage |
Post subject:
Posted: Thu Jun 07, 2007 7:37 am
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General |
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Joined: Fri Feb 17, 2006
12:07 pm Posts: 218 Location: London UK
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Hi panagiotis. I hope your exams were not too
painful I will sketch the layout in a Word document
and email it to you as an attachment. BTW: not
sure if that scanning method will work. It might
if the outer left VCO were "up-tuned" say 1kHz and
the outer right were "down-tuned" 1 kHz. Even
so, the scanning rate would be 360000 degrees per
second. There are always problems if the elements
of a phased array are out of phase by more than
a limited amount. The pattern resembles something
like chewed dates. From your comment, it is now
clear you wish the elements to be arranged in a
line and not in a "box" format.
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panagiotis |
Post subject:
Posted: Thu Jun 07, 2007 10:05 am
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Joined: Thu May 10, 2007
11:14 am Posts: 8 |
Hi Nubbage, Ok, I wait for your e-mail. I
have one more question.. With what program have
you designed the array? It would be very good
for my diploma thesis to conclude the design!
Also, I have found many papers, which have applications
like this. The maximum beam scanning with this method
is about +-30 degrees, because the maximum inter-element
phase shift is 90 degrees.
thanks
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nubbage |
Post subject:
Posted: Mon Jun 18, 2007 9:11 am
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Joined: Fri Feb 17, 2006
12:07 pm Posts: 218 Location: London UK
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Hi panagiotis email was sent off to you last
week. Please confirm if it was received OK.
It had a sketch drawing in a Word file attachment.
I am currently looking at the radiation pattern
envelope.
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Posted 11/12/2012
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